This invention relates in general to anchors that are bored into the ground and more specifically to a ground anchor having a cap for compressing soil above an auger wherein the cap is downward biased so as to still provide compression during strain on the anchor and, preferably also, wherein the cap can tilt so as to align with the contour of the grade.
Ground anchors of the auger type tend to loosen the soil as the auger is screwed into the earth. This tends to make the anchor shaft less stable. Particularly, the upper end of the anchor shaft may be able to move back and forth laterally in the loosened soil and thereby loosen the anchor such that the anchor becomes ineffective. Our above-identified co-pending application, teaches the use of a compression cap on the upper end of the shaft. The compression cap is pulled against the top of the disturbed soil by the auger action and bears against and compresses the soil that has been disturbed by the auger. This soil compaction greatly increases the stability of the upper end of the anchor shaft. However, in conditions of large fluctuating forces on anchor lines, such as encountered during a hurricane or tornado, anchors pull out at a undesirable rate.
Accordingly, there has been a need for an improved ground anchor.
The invention is a ground anchor for boring in the soil, and it generally includes an elongate shank having an auger on its lower end and a attachment mechanism on its upper end for attachment of anchor lines, a compression cap, and biasing means, such as a spring, operating between the upper end of the shank and the compression cap for biasing the cap in a downward direction so as to compress soil between the cap and the auger.
The compression cap is a generally disk-shaped plate of uniform thickness having an aperture freely journaling it on the shank above the soil such that said plate can freely tilt through a tilt angle to align with the surface of the soil. Preferably, a side slot provides entry of the shaft to the central aperture.
The cap has a generally planar downward facing surface for compressing soil between the cap and the auger blades. Preferably, the cap has peripheral side walls extending upwards or downwards from the perimeter of the plate for bearing against the soil for presenting a larger side surface area than the plate for preventing lateral movement.
The biasing means may be one or more springs. Coil, leaf or torsion springs may be used. The spring biases the cap in a downward direction so that soil between the cap and the auger remains compacted at all times. This compacted soil helps prevent lateral movement of shaft 21 and bears laterally outward to prevent upward movement of the auger.
Other features and many attendant advantages of the invention will become more apparent upon a reading of the following detailed description together with the drawings wherein like reference numerals refer to like parts throughout.